<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

</body>

</html>
<script>
    (function () {
        function tank() {
            this.dom = null
            this.speed = 0
            this.color = ''
            this.run = function () { }
        }

        var instance = null

        function getInstance() {
            return instance ? instance : (instance = new tank())
        }

        // window.SingleTon = { getInstance }
        window.getInstance = getInstance
    })()

    var a = getInstance()
    var b = getInstance()
    var c = getInstance()
    // var a = SingleTon.getInstance()
    // var b = SingleTon.getInstance()
    // var c = SingleTon.getInstance()

    console.log(a, b, c);
    console.log(a == b);
    console.log(a == c);
    console.log(b == c);

</script>